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*DECK ALGPT
      SUBROUTINE ALGPT(NGPT,XINF,XSUP,ZGKSI,WGKSI)
*
*-----------------------------------------------------------------------
*
*Purpose:
* returns gauss integration points and weights for integration limits
* specified and to the order specified
*
*Copyright:
* Copyright (C) 1991 Ecole Polytechnique de Montreal
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version
*
*Author(s): R. Roy and O. Vagner
*
*Reference:
* integral of F(X)DX , from XINF to XSUP is given by summ from i=1 to
* NGPT of F(ZGKSI(I))*WGKSI(I)
* the points ZGKSI and weights WGKSI are generated according
* to the technique described in Handbook of mathematical functions
* M. Abramowitz and I. Stegun, Dover Publication Inc. (1972);
* all points and weights are taken from A.H. Stroud and D. Secrest,
* gaussian quadrature formulas, Prentice-Hall (1966).
*
*Parameters: input
* NGPT    number of gauss points
* XINF    lower integration limit
* XSUP    upper integration limit
*
*Parameters: output
* ZGKSI   integration points
* WGKSI   integration weights
*
*-----------------------------------------------------------------------
*
*----
*  SUBROUTINE ARGUMENTS
*----
      INTEGER NGPT
      REAL XINF,XSUP,ZGKSI(NGPT),WGKSI(NGPT)
*----
*  LOCAL VARIABLES
*----
      PARAMETER ( I2= 1, I3= 2, I4= 3, I5= 5, I6= 7, I7=10, I8=13,
     >            I9=17,I10=21,I11=26,I12=31,I13=37,I14=43,I15=50,
     >           I16=57,I17=65,I18=73,I19=82,I20=91,I24=101,I28=113,
     >           I32=127,I64=143,IFN=174)
      PARAMETER ( HALF=0.5E0, TWO=2.0E0 )
      REAL        RZKSI(IFN),RWKSI(IFN),FW,FC
      CHARACTER   CERROR*4
      SAVE        RZKSI,RWKSI
C  N=2
      DATA (RZKSI(I),I=I2,I3-1)     /        .577350269189626E0/
      DATA (RWKSI(I),I=I2,I3-1)     /       1.000000000000000E0/
C  N=3
      DATA (RZKSI(I),I=I3,I4-1)     /        .774596669241483E0/
      DATA (RWKSI(I),I=I3,I4-1)     /        .555555555555556E0/
C  N=4
      DATA (RZKSI(I),I=I4,I5-1)     /        .339981043584856E0,
     >                                       .861136311594053E0/
      DATA (RWKSI(I),I=I4,I5-1)     /        .652145154862546E0,
     >                                       .347854845137454E0/
C  N=5
      DATA (RZKSI(I),I=I5,I6-1)     /        .538469310105683E0,
     >                                       .906179845938664E0/
      DATA (RWKSI(I),I=I5,I6-1)     /        .478628670499366E0,
     >                                       .236926885056189E0/
C  N=6
      DATA (RZKSI(I),I=I6,I7-1)     /        .238619186083197E0,
     >                                       .661209386466265E0,
     >                                       .932469514203152E0/
      DATA (RWKSI(I),I=I6,I7-1)     /        .467913934572691E0,
     >                                       .360761573048139E0,
     >                                       .171324492379170E0/
C  N=7
      DATA (RZKSI(I),I=I7,I8-1)     /        .405845151377397E0,
     >                                       .741531185599394E0,
     >                                       .949107912342759E0/
      DATA (RWKSI(I),I=I7,I8-1)     /        .381830050505119E0,
     >                                       .279705391489277E0,
     >                                       .129484966168870E0/
C  N=8
      DATA (RZKSI(I),I=I8,I9-1)     /        .183434642495650E0,
     >                                       .525532409916329E0,
     >                                       .796666477413627E0,
     >                                       .960289856497536E0/
      DATA (RWKSI(I),I=I8,I9-1)     /        .362683783378362E0,
     >                                       .313706645877887E0,
     >                                       .222381034453374E0,
     >                                       .101228536290376E0/
C  N=9
      DATA (RZKSI(I),I=I9,I10-1)    /        .324253423403809E0,
     >                                       .613371432700590E0,
     >                                       .836031107326636E0,
     >                                       .968160239507626E0/
      DATA (RWKSI(I),I=I9,I10-1)    /        .312347077040003E0,
     >                                       .260610696402935E0,
     >                                       .180648160694857E0,
     >                                       .081274388361574E0/
C  N=10
      DATA (RZKSI(I),I=I10,I11-1)   /        .148874338981631E0,
     >                                       .433395394129247E0,
     >                                       .679409568299024E0,
     >                                       .865063366688985E0,
     >                                       .973906528517172E0/
      DATA (RWKSI(I),I=I10,I11-1)   /        .295524224714753E0,
     >                                       .269266719309996E0,
     >                                       .219086362515982E0,
     >                                       .149451349150581E0,
     >                                       .066671344308688E0/
C  N=11
      DATA (RZKSI(I),I=I11,I12-1)   /
     >                    .978228658146057E0,.887062599768095E0,
     >                    .730152005574049E0,.519096129206812E0,
     >                    .269543155952345E0/
      DATA (RWKSI(I),I=I11,I12-1)    /
     >                    .055668567116174E0,.125580369464905E0,
     >                    .186290210927734E0,.233193764591990E0,
     >                    .262804544510247E0/
C  N=12
      DATA (RZKSI(I),I=I12,I13-1)   /
     >                    .125233408511469E0,.367831498998180E0,
     >                    .587317954286617E0,.769902674194305E0,
     >                    .904117256370475E0,.981560634246719E0/
      DATA (RWKSI(I),I=I12,I13-1)   /
     >                    .249147045813403E0,.233492536538355E0,
     >                    .203167426723066E0,.160078328543346E0,
     >                    .106939325995318E0,.047175336386512E0/
C  N=13
      DATA (RZKSI(I),I=I13,I14-1)    /
     >                    .984183054718588E0,.917598399222978E0,
     >                    .801578090733310E0,.642349339440340E0,
     >                    .448492751036447E0,.230458315955135E0/
      DATA (RWKSI(I),I=I13,I14-1)    /
     >                    .040484004765316E0,.092121499837728E0,
     >                    .138873510219787E0,.178145980761946E0,
     >                    .207816047536888E0,.226283180262897E0/
C  N=14
      DATA (RZKSI(I),I=I14,I15-1)     /
     >                    .986283808696812E0,.928434883663573E0,
     >                    .827201315069765E0,.687292904811685E0,
     >                    .515248636358154E0,.319112368927890E0,
     >                    .108054948707344E0/
      DATA (RWKSI(I),I=I14,I15-1)     /
     >                    .035119460331752E0,.080158087159760E0,
     >                    .121518570687903E0,.157203167158193E0,
     >                    .185538397477938E0,.205198463721296E0,
     >                    .215263853463158E0/
C  N=15
      DATA (RZKSI(I),I=I15,I16-1)     /
     >                    .987992518020485E0,.937273392400706E0,
     >                    .848206583410427E0,.724417731360170E0,
     >                    .570972172608539E0,.394151347077563E0,
     >                    .201194093997434E0/
      DATA (RWKSI(I),I=I15,I16-1)     /
     >                    .030753241996117E0,.070366047488108E0,
     >                    .107159220467172E0,.139570677926154E0,
     >                    .166269205816994E0,.186161000015562E0,
     >                    .198431485327111E0/
C  N=16
      DATA (RZKSI(I),I=I16,I17-1)   /
     >                    .095012509837637E0,.281603550779259E0,
     >                    .458016777657227E0,.617876244402644E0,
     >                    .755404408355003E0,.865631202387832E0,
     >                    .944575023073233E0,.989400934991650E0/
      DATA (RWKSI(I),I=I16,I17-1)   /
     >                    .189450610455068E0,.182603415044924E0,
     >                    .169156519395003E0,.149595988816577E0,
     >                    .124628971255534E0,.095158511682493E0,
     >                    .062253523938648E0,.027152459411754E0/
C  N=17
      DATA (RZKSI(I),I=I17,I18-1)    /
     >                    .990575475314417E0,.950675521768768E0,
     >                    .880239153726986E0,.781514003896801E0,
     >                    .657671159216691E0,.512690537086477E0,
     >                    .351231763453876E0,.178484181495848E0/
      DATA (RWKSI(I),I=I17,I18-1)    /
     >                    .024148302868548E0,.055459529373987E0,
     >                    .085036148317179E0,.111883847193404E0,
     >                    .135136368468525E0,.154045761076810E0,
     >                    .168004102156450E0,.176562705366993E0/
C  N=18
      DATA (RZKSI(I),I=I18,I19-1)    /
     >                    .991565168420930E0,.955823949571397E0,
     >                    .892602466497556E0,.803704958972523E0,
     >                    .691687043060353E0,.559770831073947E0,
     >                    .411751161462843E0,.251886225691505E0,
     >                    .084775013041735E0/
      DATA (RWKSI(I),I=I18,I19-1)    /
     >                    .021616013526483E0,.049714548894970E0,
     >                    .076425730254889E0,.100942044106287E0,
     >                    .122555206711478E0,.140642914670651E0,
     >                    .154684675126265E0,.164276483745833E0,
     >                    .169142382963143E0/
C  N=19
      DATA (RZKSI(I),I=I19,I20-1)    /
     >                    .992406843843584E0,.960208152134830E0,
     >                    .903155903614818E0,.822714656537143E0,
     >                    .720966177335229E0,.600545304661681E0,
     >                    .464570741375961E0,.316564099963630E0,
     >                    .160358645640225E0/
      DATA (RWKSI(I),I=I19,I20-1)    /
     >                    .019461788229726E0,.044814226765700E0,
     >                    .069044542737641E0,.091490021622450E0,
     >                    .111566645547334E0,.128753962539336E0,
     >                    .142606702173607E0,.152766042065860E0,
     >                    .158968843393954E0/
C  N=20
      DATA (RZKSI(I),I=I20,I24-1)   /
     >                    .076526521133497E0,.227785851141645E0,
     >                    .373706088715420E0,.510867001950827E0,
     >                    .636053680726515E0,.746331906460151E0,
     >                    .839116971822219E0,.912234428251326E0,
     >                    .963971927277914E0,.993128599185095E0/
      DATA (RWKSI(I),I=I20,I24-1)   /
     >                    .152753387130726E0,.149172986472604E0,
     >                    .142096109318382E0,.131688638449177E0,
     >                    .118194531961518E0,.101930119817240E0,
     >                    .083276741576705E0,.062672048334109E0,
     >                    .040601429800387E0,.017614007139152E0/
C  N=24
      DATA (RZKSI(I),I=I24,I28-1)   /
     >                    .995187219997021E0,.974728555971309E0,
     >                    .938274552002733E0,.886415527004401E0,
     >                    .820001985973903E0,.740124191578554E0,
     >                    .648093651936975E0,.545421471388839E0,
     >                    .433793507626045E0,.315042679696163E0,
     >                    .191118867473616E0,.064056892862605E0/
      DATA (RWKSI(I),I=I24,I28-1)   /
     >                   .012341229799987E0,.028531388628934E0,
     >                   .044277438817420E0,.059298584915437E0,
     >                   .073346481411080E0,.086190161531953E0,
     >                   .097618652104114E0,.107444270115966E0,
     >                   .115505668053726E0,.121670472927803E0,
     >                   .125837456346828E0,.127938195346752E0/
C  N=28
      DATA (RZKSI(I),I=I28,I32-1)   /
     >                   .996442497573954E0,.981303165370873E0,
     >                   .954259280628938E0,.915633026392132E0,
     >                   .865892522574395E0,.805641370917179E0,
     >                   .735610878013632E0,.656651094038865E0,
     >                   .569720471811402E0,.475874224955118E0,
     >                   .376251516089079E0,.272061627635178E0,
     >                   .164569282133380E0,.055079289884034E0/
      DATA (RWKSI(I),I=I28,I32-1)   /
     >                   .009124282593094E0,.021132112592771E0,
     >                   .032901427782304E0,.044272934759004E0,
     >                   .055107345675717E0,.065272923966999E0,
     >                   .074646214234569E0,.083113417228901E0,
     >                   .090571744393033E0,.096930657997930E0,
     >                   .102112967578061E0,.106055765922846E0,
     >                   .108711192258294E0,.110047013016475E0/
C  N=32
      DATA (RZKSI(I),I=I32,I64-1)   /
     >                    .048307665687738E0,.144471961582796E0,
     >                    .239287362252137E0,.331868602282128E0,
     >                    .421351276130635E0,.506899908932229E0,
     >                    .587715757240762E0,.663044266930215E0,
     >                    .732182118740290E0,.794483795967942E0,
     >                    .849367613732570E0,.896321155766052E0,
     >                    .934906075937740E0,.964762255587506E0,
     >                    .985611511545268E0,.997263861849482E0/
      DATA (RWKSI(I),I=I32,I64-1)   /
     >                    .096540088514728E0,.095638720079275E0,
     >                    .093844399080805E0,.091173878695764E0,
     >                    .087652093004404E0,.083311924226947E0,
     >                    .078193895787070E0,.072345794108849E0,
     >                    .065822222776362E0,.058684093478536E0,
     >                    .050998059262376E0,.042835898022227E0,
     >                    .034273862913021E0,.025392065309262E0,
     >                    .016274394730906E0,.007018610009470E0/
C  N=64
      DATA (RZKSI(I),I=I64,IFN)   /
     > .024350292663424E0,.072993121787799E0,.121462819296121E0,
     > .169644420423993E0,.217423643740007E0,.264687162208767E0,
     > .311322871990211E0,.357220158337668E0,.402270157963992E0,
     > .446366017253464E0,.489403145707053E0,.531279464019894E0,
     > .571895646202634E0,.611155355172393E0,.648965471254657E0,
     > .685236313054233E0,.719881850171611E0,.752819907260532E0,
     > .783972358943341E0,.813265315122798E0,.840629296252580E0,
     > .865999398154093E0,.889315445995114E0,.910522137078503E0,
     > .929569172131940E0,.946411374858403E0,.961008799652054E0,
     > .973326827789911E0,.983336253884626E0,.991013371476744E0,
     > .996340116771955E0,.999305041735772E0/
      DATA (RWKSI(I),I=I64,IFN)   /
     > .048690957009140E0,.048575467441503E0,.048344762234803E0,
     > .047999388596458E0,.047540165714830E0,.046968182816210E0,
     > .046284796581314E0,.045491627927418E0,.044590558163757E0,
     > .043583724529323E0,.042473515123654E0,.041262563242624E0,
     > .039953741132720E0,.038550153178616E0,.037055128540240E0,
     > .035472213256882E0,.033805161837142E0,.032057928354852E0,
     > .030234657072402E0,.028339672614259E0,.026377469715055E0,
     > .024352702568711E0,.022270173808383E0,.020134823153530E0,
     > .017951715775697E0,.015726030476025E0,.013463047896719E0,
     > .011168139460131E0,.008846759826364E0,.006504457968978E0,
     > .004147033260562E0,.001783280721696E0/
*
      IDEP=0
      IFIN=0
      FW=HALF*(XSUP-XINF)
      FC=HALF*(XSUP+XINF)
      IF( NGPT.EQ. 1 ) THEN
        ZGKSI(1)=FC
        WGKSI(1)=TWO*FW
        RETURN
      ELSE IF( NGPT.EQ. 2 ) THEN
        IDEP=I2
        IFIN=I3-1
      ELSE IF( NGPT.EQ. 3 ) THEN
        IDEP=I3
        IFIN=I4-1
      ELSE IF( NGPT.EQ. 4 ) THEN
        IDEP=I4
        IFIN=I5-1
      ELSE IF( NGPT.EQ. 5 ) THEN
        IDEP=I5
        IFIN=I6-1
      ELSE IF( NGPT.EQ. 6 ) THEN
        IDEP=I6
        IFIN=I7-1
      ELSE IF( NGPT.EQ. 7 ) THEN
        IDEP=I7
        IFIN=I8-1
      ELSE IF( NGPT.EQ. 8 ) THEN
        IDEP=I8
        IFIN=I9-1
      ELSE IF( NGPT.EQ. 9 ) THEN
        IDEP=I9
        IFIN=I10-1
      ELSE IF( NGPT.EQ.10 ) THEN
        IDEP=I10
        IFIN=I11-1
      ELSE IF( NGPT.EQ.11 ) THEN
        IDEP=I11
        IFIN=I12-1
      ELSE IF( NGPT.EQ.12 ) THEN
        IDEP=I12
        IFIN=I13-1
      ELSE IF( NGPT.EQ.13 ) THEN
        IDEP=I13
        IFIN=I14-1
      ELSE IF(NGPT.EQ.14 ) THEN
        IDEP=I14
        IFIN=I15-1
      ELSE IF(NGPT.EQ.15 ) THEN
        IDEP=I15
        IFIN=I16-1
      ELSE IF(NGPT.EQ.16 ) THEN
        IDEP=I16
        IFIN=I17-1
      ELSE IF(NGPT.EQ.17 ) THEN
        IDEP=I17
        IFIN=I18-1
      ELSE IF(NGPT.EQ.18 ) THEN
        IDEP=I18
        IFIN=I19-1
      ELSE IF(NGPT.EQ.19 ) THEN
        IDEP=I19
        IFIN=I20-1
      ELSE IF( NGPT.EQ.20 ) THEN
        IDEP=I20
        IFIN=I24-1
      ELSE IF( NGPT.EQ.24 ) THEN
        IDEP=I24
        IFIN=I28-1
      ELSE IF( NGPT.EQ.28 ) THEN
        IDEP=I28
        IFIN=I32-1
      ELSE IF( NGPT.EQ.32 ) THEN
        IDEP=I32
        IFIN=I64-1
      ELSE IF( NGPT.EQ.64 ) THEN
        IDEP=I64
        IFIN=IFN
      ELSE
        WRITE(CERROR,'(I4)') NGPT
        CALL XABORT('ALGPT:INVALID NBR.OF GAUSS PTS.='//CERROR//'   ***
     >  1 TO 20,24,28,32,64 PTS. ARE PERMITTED')
      ENDIF
C------
C  INITIALIZE ZGKSI AND WGKSI STARTING FROM BOTTOM WITH NEGATIVE
C  AND FINISHING WITH POSITIVE
C------
      IUP=1
      IDN=NGPT
      DO 100 I=IFIN,IDEP,-1
        ZGKSI(IUP)=-FW*RZKSI(I)+FC
        WGKSI(IUP)=FW*RWKSI(I)
        ZGKSI(IDN)=FW*RZKSI(I)+FC
        WGKSI(IDN)=FW*RWKSI(I)
        IUP=IUP+1
        IDN=IDN-1
 100  CONTINUE
C------
C  FOR ODD NGPT, CENTRAL POINT IS 0.0 AND WEIGHT IS (2.0-TOTAL WEIGHT)
C------
      IF(IUP.EQ.IDN) THEN
        ZGKSI(IUP)=FC
        DO 110 I=1,IUP-1
          FW=FW-WGKSI(I)
 110    CONTINUE
        WGKSI(IUP)=TWO*FW
      ENDIF
      RETURN
      END